Nazo is a mysterious blue-gray glowing hedgehog-like creature that appeared in an early trailer for Sonic X. The image also appeared on Sega's Japanese website and was entitled "Nazo.jpg", which has led to some fans assuming that Nazo was to be this character's name. This is however questionable because the word "Nazo" means "mystery" in Japanese, leading others to believe "Nazo" was only used as a file image as a placeholder for the actual name.
He did not appear in the actual show and Sega has not given any information about him; so much debate has followed about who he was to be. Many assume that he was to be a villain, or Hyper Sonic, but there is nothing to support these but one's interpretation of the image. Nazo bears little resemblance to any of the characters and has spikes that branch from both sides of his back.